Analysis of the genetic control of autoimmune disease and plasmacytoma induction in mice is being made at two general levels. Firstly to evaluate the cellular level of genetic controlled traits, with particular regard to suppressor T cell activation, role of histamine receptors, macrophage expressed traits controlling ability to respond and infulence of T cells on antibody responsiveness; and secondly a genetic analysis of autoimmune development, ability to undergo tolerance, and susceptibility to tumor induction, in allotype and/or histocompatibility congenic lines of mice. Linkage studies of these various parameters are also proceeding in F2 and backcross mice. Development of a series of allotype congenic mice continues for use in these and related studies.